Spring-tensioning device for self-playing stringed instruments



Nov. 19, 1929. c. P. CORWIN r 1,736,580

STRING TENSIONING DEVICE FOR SELF PLAYING STRINGED INSTRUMENTS Original Filed March 16, 1927 Z'Sheets-Sheet l.

27 3521 I 61 i a 4 10 SI" new 01/ a (bra/11w.

Nov. 19, 1929. c. P. CORWIN 1,736,580

STRING TENSIONING DEVICE FOR SELF PLAYING STRINGED INSTRUMENTS Original Filed March 16. 1927 -2 Sheets-Sheet 2 5| u new two (2 1 I'WI'II.

Patented Nov. 19, 1929 UNITE STATES PATEN ()FFIC CHARLES P. CORWIN, 0F BROWNWOOD, TEXAS Original application filed March 16, 1927, Serial No. 175,782. Divided and this application filed February 28, 1928. Serial No. 257,661.

This application is a division of an application, Serial No. 175,782, filed by me March 16, 1927, the present invention relating particularly to the tension mechanism of a selfplaying stringed instrument, and having for its object the provision of means whereby the strings of the instrument will be automatically maintained in tune. The invention is illustrated in the accompanying drawings and will be hereinafter fully described, the novel features being defined in the appended claims.

In the accompanying drawings:

Figure 1 is a side elevation, partly in section, of one embodiment of the invention;

Fig. 2 is a plan view of the same;

Fig. 3 is an enlarged section on the line 3-3 of Fig. 1;

Fig. 4 is a section on the line 4-4 of Fig. 3, and

Fig. 5 is a section on the line 5-5 of Fig. 4.

In the drawings, the numeral 10 denotes a shelf rigidly secured-within a suitable casing and upon which a bed'plate 11 is fixed, a post or standard 14 rising from one end of the bed plate to support the head of the violin.

The post 14 is of a somewhat flared forma tion at its upper end and at said end is formed with the lateral longitudinally extending flanges 27, while the extreme forward portion of the said post is beveled or cut away between the ends thereof at its top, as indi cated at 28, to accommodate the head 29 of the violin. Brackets 30 are provided at the head end of the instrument, and these brackets are arranged in pairs with one member of each pair on each side of the post, each bracket having a foot portion 31 shaped to fit around the edge of the respective flange 27 and carrying in its under side a set bolt 32 adapted to be turned home against the under side of the respective flange whereby the bracket will be secured in place. Immediately above the flanges 27 one bracket on each side of the instrument is equipped with a set bolt 33 arranged to bear against the side of the head 29 whereby the head will be firmly clamped and supported in the desired position, each of said clamping screws or bolts being equipped at its inner end with a felt pad 34. It will thus be seen that the violin is supported firmly without any contact with metal surfaces so that all metallic quality will be eliminated from the notes produced by the instrument. If desired, the instrument may be further supported by a small bolt or threaded post 35 fitted in the top of the standard 14 at the inner side of the same and bearing against the bottom of the head 29 at the ]11IlCti0I1 of the same with the neck 36, this post or supporting screw being equipped with afelt pad, as will be understood.

The upper end of each bracket 30 is enlarged to form a collar or hub member 37 receiving the enlarged head 38 of a pin 39 whichprojects inwardly from the bracket and is equipped with a smooth bore of relatively small diameter. The head 38 is provided with a central bore or chamber 40 and in the said bore or chamber is mounted a turning pin 41 having a knurled head 42 on its outer end whereby it may be easily manipulated. This turning pin or plug 41 is provided with a central threaded bore 43 receiving the outer threaded end of a pin 44 extending axially through the pin 39, as clearly shown in Fig. 4. The plug 41 is also provided With an annular groove 45 receiving the inner end of a set screw 46 mounted in the hub 37 whereby rotation of the plug will be permitted but endwise movement thereof will be prevented. The inner end of the pin 44 is fixed to the inner closed end 46 of a thimble 47 which fits closely around the pin 39 and is provided circumferentially with raceways receiving bearing balls 48. Fitting about the balls 48 is a sleeve or hub 49 fixed to or formed integral with a disk 50 from the inner side of which projects a central peg 51 having a spirally disposed groove 52 upon its circumference to receive a violin string, and it will be noted that the groove 52 is so disposed that when the string is wound thereon it will move axially of the peg toward the disk, the inner end of the sleeve or hub member 49 being disposed initially close to or against the inner end of the head 38 and the collar or hub 49, as shown in Fig. 4. The disk 50 is provided on its outer face with marginal lugs 53 arranged equi-distantly about the entire circumferential extent of the disk and providing a clear space 54 at their inner sides around the sleeve or hub 49. An outer disk 55 is provided to mate with the disk 50, and this disk 55 is provided with similar lugs 56 which are arranged alternately with the lugs 53 so that the two disks and the lugs will constitute a grooved pulley, the working diameter of which may be varied by shifting the disks relatively toward. each other or apart. The outer disk 55 is provided with a central opening whereby it may fit around the hub or sleeve 49, and this opening is threaded to be engaged with a spool or drum 57 which fits closely about the sleeve or hub 49 and is equipped at its outer end with an enlarged head 58 whereby it may be turned as desired. In the outer circumference of the sleeve 49 near the outer end thereof is-an annular groove 59. which receives the end of a set screw 60 secured in the head 58 sothat rotation of the spool or drum upon the sleeve 49 is permitted but relative endwise movement is prevented. It will now be seen that, if the head 58 be rotated about the sleeve 49, the spool 57 will be also rotated and by reason of the threaded engagement between the spool and the disk 55 the latter will be caused to move toward or from: the. disk 50. The outer edges or surfaces of the lugs 53and 56 are inclined; so that they converge toward the centers of the disks therebydefining a groove in which a cable 61 may be disposed, one end of the cable being, of course, secured to one of the lugs 53' or 56 in any convenient manner. This cable is formed of a spring wire and is wrapped about the pulley less than. one full turn and arranged to depend from the pulley at the outer side of the respective bracket 30, a weight 62 being attached to. the lower end of each wire and thereby serving to maintain the same taut at all times. These weights will be properly adjusted so as to maintain the normal tension upon the violin string which is attached to. the respective peg 51 and stretching of the string or the effects of temperature variations thereon will. thus be automatically compensated by the weights and spring wires. The strings will be initially tuned by hand turning of the disks 50 and 55 so that the strings will be wound upon the respective pegs 51- to be given the proper tension, and then, by rotating the head 58, the disk 55 may be caused to move towards or from the disk 50 so that the weights 62 will maintain the tension of'the string. at all times. The strings 63 are disposed above the neck 36 of the instrument and extend from the respective pegs 51 to the tailpiece (not shown).

Having thus described the invention, I claim:

1. In a seltplaying musical instrument,

the combination of a body, strings supported over the body, pegs having the strings attached thereto and wound thereon, means to rotate the pegs for imparting tension to the strings, and yieldable means for maintaining the tension.

2-. In a self-playing musical instrument, the combination of a body, supports for the same, strings mounted above the body, expansible pulleys carried by the body supports, pegs disposed axially of said pulleys and carried thereby and having the strings attached to and wound thereon, and means attached to the pulleys for yiel'dably maintaining the tension in the strings.

3. In. a self-playing musical instrument, the combination of a body, supports for the same, strings. above the body, pulleys mounted. on the supports, pegs secured to said pulleys axially thereof and provided with circumferential grooves extending spirally toward the pulleys, the strings being attached to said pegs and winding in said grooves whereby to wind toward the pulleys, and means actingon the pulleys to maintain the tension in the strings.

4:. In a self-playin musical instrument, the combination of a body, supports for the same, strings mounted above the body,

pulleys mounted on: the supports for the head of the body and consisting of mating members having interengaging elements on their opposed faces, pegs carried axially by said pulleys and having the violin strings attached thereto, flexible elements attached to and extending circumferentially of the interengaging elements on the disks of the pulleys, means for maintaining tension on said flex ible elements, and means for adjusting the pulley disks-toward or from each other.

5. In a self-playin musical instrument, the combination of a body, supports for the same, strings disposed above the body, sleeves carried by the supports, disks having.- hub members encircling the respective sleeves, each disk having a peg at its center to which a string is attached, an externally threaded spool rot-atably mounted upon the hub of each said disk and held against relative endwise movement, a mating 'disk mounted upon said threaded spool whereby to shift toward or from the first-mentioned disk as the spool is rotated, and means for axially shifting the said sleeve.

6. In a self-playing musical instrument, the combination of a body, supports for the same, strings disposed above the body, pins secured in the supports for the head of the body, sleeves each fitted about one of said pins, a rod fixed to each said sleeve and extending through the said pin and having its outer end threaded, a plug engaged with the threaded end of said pin and held against endwise movement, an expansible pulley hav ing a hub member encircling said sleeve, a peg on said pulley to which a string is attached, means for expanding or contracting the pulley, and a tension device suspended on the pulley.

In testimony whereof I aflix my signature.

CHARLES P. CORWIN. 1 8.] 

